Results of a necropsy released this week show that she died of natural causes — congestive heart failure brought on by her age, said Tom Cooley, a pathologist for the state Department of Natural Resources and Environment.

“I’m very pleased that she was nine years old which, for a wolverine, is getting up there in years,” said Jeff Ford, a Deckerville High School science teacher who tracked the animal for years, sharing pictures and video with his students and others.

“She had a chance to have a pretty good life in the swamp,” Ford said.

Cooley conducted the necropsy at a lab on the campus of Michigan State University in East Lansing. The animal’s carcass had already been skinned. Her skeleton will be put on display at the MSU museum.

“The average life span for a wild wolverine is 7-11 years ... She was in the middle of that,” Cooley said. “The changes that we saw could be consistent with an old animal.”

The technical cause of death was degenerative cardiomyopathy, or a chronic breakdown of the muscle of the heart. She also had an enlarged liver.

Tests for poison came back negative.

“We ran everything under the sun on this animal,” due to its rarity in the state, Cooley said.

Previous DNA testing indicated the animal’s genetic origin was from a vast area of Ontario and Manitoba, where wolverines are a little more common but still considered rare.

Arnie Karr, a DNRE biologist, believes the wolverine may have been a released exotic pet. The animal was found semi-submerged on the downstream side of a beaver dam, but there was no evidence of drowning, Cooley said. She was apparently on the beaver dam when she died, and fell into the water afterwards, he said.

Karr declined to identify the taxidermist who’s preparing the animal for display. He said he has “no idea” when the famous wolverine may arrive at the Bay City state park’s Visitor Center.

Ford was in the lab when the necropsy was performed, and filmed the procedure for one last science lesson on the creature.

“I have an hour and 15 minutes,” he said. “I was only about six inches from scalpel the whole time.

“I showed it to our science class. The kids were absolutely fascinated.”

Ford said the necropsy was a kind of closure to his long work in tracking the animal.

“I’d rather have that than her disappearing and never knowing what happened to her.

“I thought I was just going to stop getting pictures of her and she was just going to disappear and die somewhere in the swamp ... or be shot, trapped or poisoned.”